From Rough Lapping to Fine Lapping: A Systematic Study on Tool-Material Compatibility and Process Parameter Optimization for Polycrystalline Diamond.

Polycrystalline diamond (PCD) has broad application prospects in semiconductors, optical windows and other advanced fields. Nevertheless, its ultrahigh hardness and chemical inertness pose significant challenges for achieving high-quality surface planarization. Although conventional mechanical lapping is widely adopted, it still suffers from poor surface quality and a lack of theoretical guidance for process parameter selection. This study presents a systematic experimental and simulation investigation on both rough and fine lapping of PCD, focusing on tool selection and process optimization. In the rough lapping stage, three types of fixed diamond abrasive discs with resin, bronze, and vitrified bonds were compared. The soft and tough resin-bonded disc yields the best performance, reducing surface roughness Ra from 420 nm to 106 nm. In the fine lapping stage, three metallic discs-Cu, Fe, and WC-Co-were evaluated. The high-stiffness WC-Co disc achieves the best results, with an Ra of 11.2 nm under conditions of 0.45 MPa and 600 r/min. Molecular dynamics (MD) simulations further reveal that increasing lapping pressure significantly enhances the material removal rate but concurrently aggravates subsurface damage (SSD), while the effect of speed is considerably smaller. Therefore, pressure emerges as the key parameter that requires balanced optimization in the fine lapping process.